For a process x(t), define survivability ratio P(t) = chance of finding x(t) within a predetermined range of x(0); Brownian motion has P(t) = t^(-1/2). For chaotic systems with Cantori trapping mechanisms, P(t) also follows a power law P(t) = t^(-p), p=1+α, with 0<α<1.
Now, assume s(t) is the drift-adjusted part of the stock price while S(t) is the unadjusted (original) stock price. In other words:
d(lnS(t)) = μ dt + ds(t),
we might be able to check the index α for the process s(t), by sampling a lot of (t=0).
Also Re: self-criticality; people have discussed (with mixed opinions) the relationship between financial markets and earthquakes (Gutenberg-Richter law). It might be worthwhile to check the survivability function of fBm. See also 1/f noises.

1 comment:
Hmm...your English sucks! Or else, how could I not understand a word of it?
:D
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